Pediatric Rheumatology Online Journal → July 2003 → Vasculitides → Kawasaki Disease → Abstract #131

THROMBOCYTOSIS OCCURS EARLY IN KAWASAKI DISEASE

R. Scuccimarri,^1,2 K. N. Watanabe Duffy,^1,2 M. Gordon,¹ M. Gibbon,¹ I. Morin,² R. Platt,² C. M. Duffy.^1,2

Rheumatology, Montreal Children's Hospital, Montreal, QC, Canada; ²McGill University, Canada

Background: Kawasaki disease (KD) is a systemic vasculitis and the leading cause of acquired heart disease in North American children. The treatment of KD includes IVIG and ASA. While there has been no consensus on the appropriate dose of ASA for the acute phase, most North American centers use high dose ASA until the patient is afebrile or until the 14^th day of illness. Here we describe the time of onset of thrombocytosis in our cohort of KD patients treated with low dose ASA and IVIG in the acute phase, and emphasize the need for earlier introduction of anti-platelet (low) doses of ASA.
Methods: A retrospective chart review was conducted of all patients admitted at our center with a diagnosis of KD between January 1985 and December 1999. Patients who either fulfilled KD diagnostic criteria or were deemed to have atypical or incomplete KD, and who were treated with low dose ASA and IVIG, were included. From these patients, those who had undergone serial platelet testing (at least 2 values within 7 days of each other) and had demonstrated thrombocytosis (platelet count 450,000) at any point were studied further.
Results: A total of 221 patients were included. Of these, 165 fulfilled platelet monitoring criteria and underwent further study. The mean day of illness in which thrombocytosis was first documented was 9.32 (range 2 - 22) with a mean platelet count of 565,394 (range 451,000 - 989,000). Interestingly, 49 (29.69%) patients had an elevated platelet count at the time of presentation which was at 6.76 days (range 2 - 17), while the mean day of illness for commencement of treatment of the total cohort was 6.61 (2 - 17).
Conclusion: The mean day of illness in which thrombocytosis occurred was lower than 9.32 days because patients did not have daily platelet counts and only the earliest documented thrombocytosis was included. Thrombocytosis can occur earlier than previously described. Therefore, introduction of anti-platelet (low) dose ASA during the acute phase of the disease seems appropriate.